The earthquake waveform data were downloaded from the European Integrated Data Archive (EIDA). We acknowledge the institutions that shared their data through EIDA. The waveform data for this region are mainly provided by the Norwegian National Seismic Network (NS), the Norwegian Seismic Array Network (NO), the Swedish National Seismic Network (UP), the Great Britain Seismic Network (GB), the Icelandic National Digital Seismograph Network, and the Danish Seismological Network (DK).